This invention relates to gaming apparatus and more particularly to that class of gaming apparatus known as slot machines wherein wheels or reels having indicia on the periphery are set into rotation and stop at locations illustrating either a winning or losing combination of the indicia.
Gaming apparatus of this type are those having mechanical wheels or reels which are set into rotation after insertion of one or more coins which activates mechanism to allow a handle to be pulled or a button to be depressed. Thereafter, the reels rotate or spin about a common axis and the rotation is subsequently stopped at angular positions which are indicated by indicia or symbols on the periphery of each reel. The angular positions of the reels determines whether or not there is a win and, if there is a win, the amount of the win or pay-out to the player.
The original reel type gaming apparatus were mechanically controlled. The reels were stopped by a braking device such as an indexing wheel fixed to each reel having a plurality of indexing grooves into which a pin of a tripping arm entered randomly, the arm being actuated by mechanical means including ratchet and pawl and spring means which timed out to release the arms and stop the rotation of the reels in sequence. Pay-outs from the apparatus were made in accordance with a pay-out schedule related to the probability of occurrence of symbols appearing on the reels after stoppage, the symbols appearing through a window on the housing of the apparatus. Subsequent developments in this art provided electromechanical constructions which used similar stopping methods, while more recently electronically operated apparatus have transitioned from control of such tripping arms by relay logic to outputs from signal generators generating a random code of numbers. In these newer electronic devices, solenoid actuated brakes have been controlled to stop each reel in sequence, and the most recent apparatus use a stepper motor to rotatably drive each reel and to stop the rotation at positions determined by a random number generator corresponding to each reel.
In the original mechanically controlled reel gaming apparatus the starting and stopping of the reel rotation occurred substantially in random fashion after the handle was pulled, and thus the particular stopping position of the reels and score was effected on a probability basis. After the reels were stopped the stopped position was detected to determine whether a pay-out was to occur. Accordingly, the hit frequency or probability of a win was based on the laws of probability. The pay-out odds and amount paid out could only be increased if the size of the reels were changed, i.e., made larger, to increase the number of stopping positions and the number of symbols displayed, if the number of reels remained constant. Of course, the number of reels could be increased to increase the odds and pay-out by changing the number of winning combinations. The lowest probability or maximum odds of a pay-out for such apparatus is a function of the number of reels (R) and the number of stop positions (N) on each reel, and is equal to the number of stop positions raised to the power equal to the number of reels, i.e., N.sup.R. Subsequent electromechanical apparatus operated on substantially the same basis except that the reels were set in motion by electrical means.
Later developments involving electronic machines utilized the probability or reel position selection resulting from random number generators. For example, Saxton et al U.S. Pat. No. 4,095,795 describes a system having a computer including a random number generator corresponding to each reel, the computer being operable to produce a random number corresponding to positions on the respective reel. The rotation of the reels is stopped at positions determined by the numbers generated. The random code generators simulate a rotation of the respective wheel through the various positions and thereafter the reel rotation is stopped in response to a simulated position. There is one position in memory corresponding to each position on the reel and therefore, the odds of stopping at a particular position, i.e., hitting a single symbol, on each reel is substantially the same as in the mechanical or electromechanical machines. The electronic gaming apparatus of Saxton et al is intended to select the combination randomly at the beginning of a cycle and to preclude disturbing that selection by manually or physically manipulating the machine by shaking or jogging it or the like. Stoppage of the reel rotations at the selected positions is controlled by position sensors and stop signals transmitted to stop solenoids or brakes.
In a later development, in order to change the probability of a hit or the odds for any particular combination to be displayed and therefore increase the pay-out for a jackpot and change the pay-out odds without increasing the size of the reels or the number of reels, Telnaes U.S. Pat. No. 4,448,419 describes an apparatus wherein the random number generators include a greater number of "virtual" positions in memory than there are actual positions on the reels. There is an actual symbol on each reel corresponding to each virtual position in memory, but there are a greater number of virtual positions in memory than there are actual positions or stops on the reels. The random number generator selects a number corresponding to a virtual position and since there are more virtual positions than actual or physical reel positions, the probabilities or odds may be changed by increasing the number of virtual positions corresponding to an actual position without changing the reels. However, there is a finite number of symbols on the virtual reel, or numbers in the random number generator, since each such symbol or number corresponds to or maps back to an actual position on the actual or physical reel. Whether there is a winner or loser and the amount won if a winner occurs is determined by the numbers generated.
In order to select the Hit Frequency, i.e., the wins per play defined as the probability of a win in any amount or the percentage of winning games to total games played, and the Pay-out Percentage, i.e., the return on input defined as the percentage of the total intake into the machine which is paid out to winning players, involves a complex reiterative or trial and error process in any of the apparatus of the prior art. The complexity increases as the number of reels increase and as the number of symbols on the reels increases. For example, consider a traditional game with three reels and twenty stops per reel, and for simplicity such consideration is here limited to a Jackpot Only type of game. This type of game has one symbol type on the reel such as a BAR. The percentage and hit frequency are changed by changing the number of BAR symbols on the reels. Since there are twenty stops on each reel, there are 20.times.20.times.20 (or 8000) possible results. If there is only one BAR on each reel only one of the 8000 results will be a winner having three BARS. Assuming a Pay-out of 200 coins, for 8000 coins played (one per game) only 200 coins will be paid out for the one winning result. The Pay-out Percentage is 200/8000 or 2.5%. Also in this case since there is one winning game out of 8000 possible games, the Hit Frequency is 1/8000 or 0.0125%.
These calculations are traditionally performed using a Pay-out table such as the following:
__________________________________________________________________________ SYMBOLS REEL 1 REEL 2 REEL 3 WINS PAY COINS OUT __________________________________________________________________________ BAR BAR BAR 1 1 1 1 200 200 Total 200 Pay-Out Percentage = 200/8000 = 2.5% Hit Frequency = 1/8000 = 0.0125% __________________________________________________________________________
If, for example, a BAR is added to the first reel the Pay-out table becomes:
__________________________________________________________________________ SYMBOLS REEL 1 REEL 2 REEL 3 WINS PAY COINS OUT __________________________________________________________________________ BAR BAR BAR 2 1 1 2 200 400 Total 2 400 Pay-Out Percentage = 400/8000 = 5.0% Hit Frequency = 2/8000 = 0.025% __________________________________________________________________________
It may be noted that the WINS column is the product of REEL 1.times.REEL 2.times.REEL 3. If there are 3 BARS on REEL 1, 4 BARS on REEL 2 and 5 BARS on REEL 3, the Pay-out table becomes:
__________________________________________________________________________ SYMBOLS REEL 1 REEL 2 REEL 3 WINS PAY COINS OUT __________________________________________________________________________ BAR BAR BAR 3 4 5 60 200 12000 Total 60 12000 Pay-Out Percentage = 12000/8000 = 150% Hit Frequency = 60/8000 = 0.75% __________________________________________________________________________
This game will thus pay out more than it takes in. The designer must now reduce the number of BARS to make the Pay-out Percentage less than 100%. For example, changing the number of BARS on REEL 2 from 4 to 3, and the number of BARS on REEL 3 from 5 to 4, results in the following:
__________________________________________________________________________ SYMBOLS REEL 1 REEL 2 REEL 3 WINS PAY COINS OUT __________________________________________________________________________ BAR BAR BAR 3 3 4 36 200 7200 Total 36 7200 Pay-out Percentage = 7200/8000 = 90% Hit Frequency = 36/8000 = 0.45% __________________________________________________________________________
This game would be profitable but not popular since with a Hit Frequency of 0.45% a player would win only one of 222 games. To increase the Hit Frequency it is necessary to add lower value pays which have a higher frequency of occurrence. For Example, assuming 2 coins are paid on a single BAR occurring on any reel, and that there are 2 BARS on each reel and that the symbol X stands for a blank the Pay-out table would be as follows:
__________________________________________________________________________ SYMBOLS REEL 1 REEL 2 REEL 3 WINS PAY COINS OUT __________________________________________________________________________ BAR X X 2 18 18 648 2 1296 X BAR X 18 2 18 648 2 1296 X X BAR 18 18 2 648 2 1296 BAR BAR BAR 2 2 2 8 200 1600 Total 1952 5488 Pay-out Percentage = 5488/8000 = 68.6% Hit Frequency = 1952/8000 = 24.4% __________________________________________________________________________
This would be a more realistic game. The Hit Frequency would be acceptable but the Pay-out Percentage would be too low. Typically Pay-out Percentages should be greater than 80% and Hit Frequency should be 15% or better although this varies with the operator of the game. The effect of adding one BAR to the first reel results in the following table:
__________________________________________________________________________ SYMBOLS REEL 1 REEL 2 REEL 3 WINS PAY COINS OUT __________________________________________________________________________ BAR X X 3 18 18 972 2 1944 X BAR X 17 2 18 612 2 1224 X X BAR 17 18 2 612 2 1224 BAR BAR BAR 3 2 2 12 200 2400 Total 2208 6792 Pay-out Percentage = 6792/8000 = 84.9% Hit Frequency = 2208/8000 = 27.6% __________________________________________________________________________
It may be noted that the change increases the WINS column for the combination BAR X X but decreases the WINS column for X BAR X and X X BAR combinations. This interaction is the reason that the Pay-out Percentage calculation is an iterative process. The designer must keep juggling values until the desired Pay-out Percentage is obtained. Adding a BAR to the third reel results in the table which follows:
__________________________________________________________________________ SYMBOLS REEL 1 REEL 2 REEL 3 WINS PAY COINS OUT __________________________________________________________________________ BAR X X 3 18 17 918 2 1836 X BAR X 17 2 17 578 2 1156 X X BAR 17 18 3 918 2 1836 BAR BAR BAR 3 2 3 18 200 3600 Total 2432 8428 Pay-out Percentage = 8428/8000 = 105.35% Hit Frequency = 2432/8000 = 30.4% __________________________________________________________________________
Thus, adding one BAR to the third reel has increased the Pay-out Percentage by more than 20% resulting in a losing game for the operator.
The situation becomes even more complex as the number of different symbol types increases. It can be seen that a machine having CHERRY, ORANGE, BELL, MELON, SINGLE BAR, DOUBLE BAR, TRIPLE BAR, and 7's on each reel strip results in a pay-out table which has grown in complexity. Trying to fine tune the Pay-out Percentage and the Hit Frequency provides a complex task.
Additionally, in prior art gaming apparatus there is no means provided wherein a player may select a pay schedule. For example, if the apparatus is set to only provide a jackpot, i.e., a Jackpot Only type of game there will be only one winning combination which is the multi-coin jackpot such as 200 coins. If the apparatus has a jackpot and lower value pays, which will have a higher frequency of occurence and a lower number of coins paid, such as two coins, the Hit Frequency (wins per play) for the jackpot will decrease if the overall Hit Frequency remains substantially the same. Similarly, if a game wherein there are intermediate value pays along with lower value pays and a jackpot, the Hit Frequency for any particular pay is determined and fixed. In order for a player to select a game having a different pay type, that is with more or less intermediate value pays, or more or less low value pays, and thus different win probabilities, the player presently must move to a different machine. There presently is no means for a player to select the pay type from that pre-existing in the machine, and for that matter, neither can the gaming facility operator, i.e., "The House." The latter would, of course, prefer to select the pay type in a machine as supply and demand dictates.